Virginia O'Hanlon from the 1890s. In 1897, at age 8, she wrote a letter to The New York Sun to ask if Santa Claus was real. The resulting editorial produced one of journalism's celebrated lines.

Jim Temple, a grandson of Virginia O’Hanlon, worried when his own grandchildren began questioning Santa’s existence.

A 6-year-old girl was sitting in the back seat of her grandfather’s truck last month, debating the existence of Santa Claus. She had questions and theories and logistic concerns, but mostly she had doubts. Her 9-year-old brother in the seat beside her was equally unconvinced. Their grandparents stared silently ahead, pretending not to listen.

It was more than just her right as an inquisitive child to question if Santa Claus was real. It was a family tradition.

The girl, Maggie Temple, is the great-great-granddaughter of the woman who has become as much a symbol of Christmas as Ebenezer Scrooge or Rudolph the Red-Nosed Reindeer: Virginia O’Hanlon, the inspiration behind one of the most famous lines in American journalism, “Yes, Virginia, there is a Santa Claus.”

In 1897, 8-year-old Virginia of 115 West 95th Street, bothered by friends who kept telling her there was no such thing as Santa, wrote a letter to The New York Sun. “Papa says ‘If you see it in The Sun it’s so.’ Please tell me the truth; is there a Santa Claus?” she wrote. The response, an unsigned editorial published on Sept. 21, 1897, and written by a former Civil War correspondent who never had children of his own, Francis P. Church, was both an exploration and an affirmation of the nature of faith and belief.

“Alas! how dreary would be the world,” Mr. Church wrote, “if there were no Santa Claus. It would be as dreary as if there were no Virginias.” He added: “Nobody sees Santa Claus, but that is no sign that there is no Santa Claus. The most real things in the world are those that neither children nor men can see.”

For generations since, Miss O’Hanlon’s descendants have quietly become ambassadors of the Christmas spirit, crossing the country to appear at events honoring her, and reading the letter and the response to children in schools and to their own children at home. They keep “Yes, Virginia” coffee mugs in their kitchen cupboards, hang “Yes, Virginia” ornaments on their Christmas trees. Come December, their names and faces turn up in newspapers and on television programs around the world, as well as in the company newsletters of their various workplaces.

Jim Temple, 71, Miss O’Hanlon’s grandson and the grandfather of Maggie Temple, remembers the day a Japanese television crew interviewed him at his home in Valatie, N.Y. Pat Hromalik, 54, Miss O’Hanlon’s youngest granddaughter, was about 7 when she appeared on television sets throughout the Rochester area, reading her grandmother’s letter. “I believe I was paid $50, and I was so excited,” said Mrs. Hromalik, who now lives in Petaluma, Calif., where the mantel above her fireplace is decorated with “Yes, Virginia” dolls and trinkets.

There are other occasional benefits and surprises. Last year, one of Miss O’Hanlon’s great-grandsons used his connection to the “Yes, Virginia” story to have his two children jump ahead in line to meet Santa at a mall in Boise, Idaho. In 2008, Mary Blair, 68, one of Miss O’Hanlon’s granddaughters, stopped at a diner in Mountain Home, Idaho, population 12,266. “Yes, Virginia,” the marquee outside read, “there is a Santa Claus.” Mrs. Blair told the management that her grandmother was the Virginia the sign referred to.

Miss O’Hanlon’s relatives look upon their fame for the most part as a kind of civic duty, standing up for a matriarch who in the public mind is forever a curious child of 8. They receive no royalties from the many products, books and animated and live-action television specials that Miss O’Hanlon’s letter and Mr. Church’s editorial inspired over the years. “How can you own something like that?” Mr. Temple said.

Miss O’Hanlon died in 1971 at the age of 81, but her legacy has guided her relatives’ lives in at least one way: Their belief in Santa, or at least the idea of Santa, is sustained into adulthood.

“Even when I knew that he wasn’t a person, there wasn’t any loss, because of growing up with this wonderful letter and beautiful response,” Mrs. Hromalik said. “When my two children got to the age where they knew there wasn’t Santa the person, they got worried about telling me that. They knew that Mom believed in Santa Claus.”

Still, even the relatives of little Virginia have just as much trouble as any other adults when it comes to navigating the Santa-belief dilemma.

Mr. Temple, a retired manager with the New York State Department of Transportation, gets choked up recalling the November afternoon when Maggie was questioning if Santa was real. Here he was, driving his grandchildren to the movies, when Maggie and James began pondering Santa’s existence, as their great-great-grandmother had famously done 113 years earlier.

“What’s going through my mind?” Mr. Temple said. “Don’t do anything that’s going to make her not believe.”

It was Libby, 13, the older sister of Maggie and James, who responded in a manner that might have made even Mr. Church proud.

“She said, ‘You know you guys, if you stop believing in Santa Claus, he can’t come to our house anymore,’ ” their grandmother, Cheryl Temple, 69, recalled. “ ‘If you believe in him, he’ll come to our house. If you don’t believe in him, he won’t come to our house.’ ”

Their great-great-grandmother was a true New Yorker. Miss O’Hanlon had an apartment in Greenwich Village. She loved baseball. She always dressed up, donning high heels and pearls. She took Jim Temple, her grandson, to his first movie and showed him how to use the subway.

Her husband left her shortly after they were married in 1913. Miss O’Hanlon, who had one child and never remarried, received a doctorate in education from Fordham University. In her 1930 doctoral dissertation, “The Importance of Play,” which examines the history and meaning of childhood play, she described the lack of playthings in many homes and neighborhoods.

“The pushcart displays an occasional doll or tea set for sale but not such as make glad the heart of childhood,” she wrote. In that last phrase she was quoting, nearly 33 years later, Mr. Church’s editorial, which refers to Santa continuing to “make glad the heart of childhood.”

In 1959, Miss O’Hanlon retired from the New York City school system after spending 43 years as a teacher and principal. In December 1969, she was hospitalized for heart trouble in Hudson, N.Y. She had been living at the time with her daughter in North Chatham, a nearby rural hamlet.

On Christmas Eve, Santa Claus, in the form of one John Harms, visited Miss O’Hanlon — her full married name was Laura Virginia O’Hanlon Douglas — and other patients at Columbia Memorial Hospital.

“I gave her a kiss on the cheek,” Mr. Harms told a reporter. “She told me she still believes in Santa Claus.”

Is There a Santa Claus? was the title of an editorial appearing in the September 21, 1897 edition of The Sun of New York. The editorial, which included the famous reply "Yes, Virginia, there is a Santa Claus", has become an indelible part of popular Christmas folklore in the United States and Canada.